Yolk-Shell Sodium Iron Sulfate@Carbon for Advanced Sodium Storage with Enhanced Capacity and Stability

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium iron sulfates (NFS) are cost-effective, high-voltage cathode materials for sodium-ion batteries.
• Current NFS materials face challenges in achieving their theoretical sodium storage capacity and stability.

Purpose of the Study:

• To develop a novel yolk-shell NFS@carbon hollow spheres (NFS@CHS) architecture.
• To enhance the electrochemical kinetics and stability of NFS cathode materials.
• To explore the potential of NFS@CHS in practical sodium-ion battery applications.

Main Methods:

• Synthesis of hierarchically porous carbon hollow spheres.
• Encapsulation of NFS nanosized particles within the carbon hollow spheres.
• Electrochemical characterization including capacity, rate retention, and cycling stability tests.

Main Results:

• The NFS@CHS composite exhibits a record-high reversible capacity of 120.2 mAh g⁻¹ at 0.1 C.
• Excellent rate capability with 65 mAh g⁻¹ retained at 20 C.
• Remarkable cycling stability exceeding 12,000 cycles.

Conclusions:

• The yolk-shell NFS@CHS architecture effectively improves sodium storage properties by enhancing electron/ion transport.
• This design offers a promising pathway for developing high-performance NFS-based cathode materials for commercial sodium-ion batteries.